extending modUser

<?xml version="1.0" encoding="UTF-8"?>
<model package="extendeduser" baseClass="xPDOObject" platform="mysql" defaultEngine="MyISAM" tablePrefix="ext_" version="1.0.0">
    <!-- extend the modUser class -->
    <object class="extUser" extends="modUser">
        <composite alias="Data" local="id" class="userData" foreign="userdata_id" cardinality="one" owner="local"/>
    </object>
    <object class="userData" table="user_data" extends="xPDOSimpleObject">
        <field key="userdata_id" dbtype="int" precision="11" phptype="integer" null="false" attributes="unsigned"/>
        <field key="firstName" dbtype="varchar" precision="50" phptype="string" null="true"/>
        <field key="lastName" dbtype="varchar" precision="50" phptype="string" null="true"/>
        <field key="title" dbtype="varchar" precision="100" phptype="string" null="true"/>
        <field key="company" dbtype="varchar" precision="100" phptype="string" null="true"/>
        <field key="registrationDate" dbtype="datetime" phptype="datetime"/>
        <field key="category1" dbtype="varchar" precision="100" phptype="string" null="true"/>
        <field key="category2" dbtype="varchar" precision="100" phptype="string" null="true"/>
        <field key="category3" dbtype="varchar" precision="100" phptype="string" null="true"/>

        <index alias="userdata_id" name="userdata_id" primary="false" unique="true" type="BTREE">
            <column key="userdata_id" length="" collation="A" null="false"/>
        </index>
        <aggregate alias="User" class= "modUser" local="userdata_id" foreign="id" cardinality="one" owner="foreign"/>
    </object>
</model>

$packageName = 'extendeduser';

$packagepath = $modx->getOption('core_path') . 'components/' . $packageName . '/';
$modelpath = $packagepath . 'model/';
if (is_dir($modelpath)) {
    $modx->addPackage($packageName, $modelpath, $prefix);
}

$c = $modx->newQuery('modUser');
$c->innerJoin('userData', 'userData', array('modUser.id = userData.userdata_id'));
$c->leftJoin('modUserProfile', 'Profile');

$c->select($modx->getSelectColumns('modUser','modUser'));
$c->select($modx->getSelectColumns('userData','userData','userData_'));
$c->select($modx->getSelectColumns('modUserProfile','Profile','Profile_'));

$c->where(array('userData.firstName' => 'Bob'));

$c->sortby('username');

$c->prepare(); echo $c->toSql();

if ($collection = $modx->getCollection('modUser',$c)){
    foreach ($collection as $object){
        $user = $object->toArray();
            echo '<pre>' . print_r($user,1) . '</pre>';
    }
}

return '';

[[!migxLoopCollection?
  &packageName=`extendeduser`
  &classname=`modUser`
  &joins=`[
    {"alias":"userData","classname":"userData","on":"modUser.id = userData.userdata_id"},
    {"alias":"Profile"}
  ]`
  &where=`{"userData.firstName":"Bob"}`
]]

$c = $modx->newQuery('userData');
$users = $modx->getCollectionGraph('userData', '{"Profile":{},"User":{}}', $c);